Natural radioactivity of coal and its by-products in the Baoji coal-fired power plant, China

Coal, bottom ash and fly ash from the Baoji coal-fired power plant, China were measured for 226 Ra, 232 Th and °K by a NaI(Tl) γ-ray spectrometer. The results show that fly ash or bottom ash contain three to six times more natural radionuclides than feed coal. The results are compared with the available data from other countries. Radium equivalent activity and external index are calculated for by-products to assess the radiation hazards arising due to the use of these ash samples in the construction of dwellings. Some fly-ash samples have radium equivalent activities and external hazard index values more than 370 Bq kg -1 and unity respectively. The absorbed dose rate at 1 m above the ash pond was (155 nGy h"1) higher than the global average value of 55 nGy h -1 and the Chinese average value of 81.5 nGy h -1 The corresponding annual external effective dose is estimated to be 0.191 mSv y -1 , which is less than that (0.46 mSv y -1 ) in areas of natural background radiation.